Dishwashing apparatus



Jan. 8, 1963 J. D. SEAL 3,072,129

DISHWASI-IING APPARATUS Filed Dec. 26, 1961F|G 'nsv 82 7 B3 s4 s4 85INVENTOR. JOHN D. SEAL ATTORNEY United States Patent 3,072,129DISHWASHING APPARATUS John D. Seal, Waukesha, Wis., assignor to GeneralElectric Company, a corporation of New York Filed Dec. 26, 1961, Ser.No. 162,103 Claims. (Cl. 134-57) This invention relates to dishwashingapparatus of the type in which the articles to be washed areautomatically subjected to a plurality of washing and rinsingoperations; and in particular, to dishwashing apparatus in which a heatmotor mechanism is used to cycle a drain valve and the total number ofwashing and rinsing operations is established by a stepping switchoperatively associated with the heat motor.

An object of the present invention is to control the washing and rinsingoperations of a dishwasher by means of a heat motor and stepping switchin lieu of the conventional time clock operated switching mechanism.

In presently known automatic dishwashers for domestic service, it iscustomary to use :an electric motor which powers a wash watercirculation pump and a waste water discharge pump. In such dishwashersit is the practice to eliminate drainage valves by utilizing a dischargepump which is direction sensitive. Such a pump has little or no pumpingetfectwhen it is rotated in the direction of rotation of the wash watercirculation pump, but is an efiicient pumping mechanism when it isdriven in the opposite direction. Therefore, since it is necessary insuch dishwashers to stop and then reverse the direction of operation ofthe main drive motor, it is the practice to use a motor of thesplit-phase induction type, for such motors are easily reversible andhave the high starting torque which is necessary for the starting loadsto which it is subjected. It is well known that such motors arerelatively expensive, and the cost of the motor is not compatible withthe ever-growing pressure to reduce manufacturing costs.

In carrying out the objectives of the present invention I am able toreduce manufacturing costs by utilizing a mechanism which is lessexpensive than the conventional timecycle mechanism, and by using a lowcost shaded pole motor. To allow for the low starting torque of such amotor, I start the motor under substantially noload, and continue it inoperation without interruption, throughout the full sequence of washingand rinsing functions of the dishwasher. I utilize a simple drain valvemechanism in association with a stepping switch which is operatedthrough a predetermined number of stepseach step representing a drainvalve operation and then interrupts the motor circuit to signify the endof the final rinsing operation. I operate the drain valve and time itsoperation by means of a heat motor which may, for example, comprise abimetal disc adapted to flex from one position to another when beingheated or cooled. It is a simple matter to arrange this heat motor to beelectrically heated continuously throughout the total washing andrinsing time; by means of a heat sink 1 can quite accurately time theduration of the closed valve condition, and by placing the heat motor ata location. in which the waste water discharge from the tub serves as acooling medium, I can quickly chill the heat motor to the extentnecessary for it to flex to return the valve to closed position. It hasbeen established, for example, that within quite acceptable commercialtolerances the valve can be closed for five minutes and opened for oneminute merely by the rate of heat absorption and dissipation to whichthe heat motor is subjected. The discharge valve is of the disc type,and I use the axial movement of the valve stem to operate a steppingswitch, which after tolling a predetermined number of valve operations,terminates the operation of the dishwasher.

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Other features and advantages will be understood from the followingdetailed description of a presently preferred embodiment of theinvention, read in connection with the accompanying drawings in which:

FIG. 1 is a front elevation of a dishwasher embodying the invention,with the lower portion in section to indicate the arrangement of theoperating mechanism;

FIG. 2 is asectional elevation of the valve and stepping switchorganization of FIG. 1, additionally schematically showing the controlcircuit; and

FIG. 3 is a somewhat schematic view of the pumping mechanism.

Referring to FIG. l, a dishwasher 1 comprises a cabinet 2 within whichis secured a tub 3 to accommodate dishes and other articles to bewashed. It will be understood that the cabinet and the tub areconventional in that the tub has an open front, afiording access forloading the on October 17, 1961, and is assigned to my assignee herein.In such a latch the switch is closed when the latch is made home andopened when the latch is operated to free the door for opening. An upperpanel 7 in the cabinet may accommodate a momentary contact pushbuttonswitch 8 to initiate operation of the dishwasher as later described.

A solenoid operated valve 10 is arranged for connection to the hot watersupply piping (not shown) of the building and its discharge tube 11terminates in a fitting (not shown) through which water is passed intothe tub. This arrangement is in all respects conventional. In the wiringdiagram portion of FIG. 2, the valve solenoid is identified by referencecharacter 12.

The dishwashing and rinsing mechanism may be as shown in applicationSerial No. 145,224, in which I am an applicant jointly with D. A.Jellies, said application being assigned to my assignee herein. Inbrief, a standpipe 14 serves as a supply pipe for the water distributionrotor 15 which is rotatably mounted thereon; said rotor has anyappropriate number of discharge orifices 16 and side-discharge reactionorifices 17. As is well known in the art, when water under pressure issupplied to the rotor 15, the reaction forces of water issuing from theorifices 17 cause the rotor to spin quite rapidly, and thus the spraysor jets issuing from the orifices 16 have wide coverage. These latterorifices are arranged to discharge against the dishes and other ware(not shown) within the tub.

The water is recirculated within the tub, and I provide a conventionalcentrifugal pump 18 which receives water through a preferably screenedinlet fitting 20 in the bottom of the tub and discharges it through theoutlet conduit 21 connected directly to the standpipe 14-. Fitting 20extends above the bottom of the tub so that during the operation of thewasher there is a volume of water in the bottom. The pump 18 is directlymounted on the shaft of the motor 22. This motor may be of the shadedpole type as previously noted. Such motors generate substantial heatduring operation and are air-cooled by means of a fan 19 on the motorshaft, said fan discharging heated air into the tub 3 through a conduit19.1. To evacuate. spent washing and rinsing liquid I provide acentrifugal pump 23 also mounted on the shaft of the motor 22. Adischarge conduit 24 extends to a point of discharge into a plumbingwaste line (not shown) as is well understood.

In view of the fact that the wash water circulation pump 18 and theWaste water discharge pump 23 are powered by the same motor, and arethus operating concurrently, means must be provided to time thedischarge of water from the tub into the pump 23, and attention is nowdirected to FIG. 2 which illustrates a valving system embodying apreferred form of the present invention.

The valve is of the disc type, comprising a disc 25 mounted on a stem 26for axial movement relative to any suitable valve seat 27 defining adrainage opening at the bottom of the tub 3. The valve stem is guidedfor movement by way of the hub 28 of a spider 3t fixed within thecylindrical portion of a drainage fitting 31. Appropriately mountedwithin a shoulder extending about the said cylindrical portion of thefitting 31 is a heat motor 33, which in the illustrated embodiment is abimetal disc having its rim seated within a sealing ring 34 of neopreneor other elastomer resistant to attack or deterioration in contact withglycerine. The heat motor forms the bottom wall of said drainagefitting, from which a conduit 35 communicates with the inlet of pump 23.The laminations of the heat motor will be arranged to assume a shape theinverse of that illustrated in FIG. 2, when the bimetal is cool. Inother words, when the bimetal is cool, it will flex to establish thevalve in closed position. Preferably, the valve seats before the disc isfully in its cool position, whereupon there is an inherent spring biastending to hold the vave closed.

The heat motor is operatively associated with the valve stem by anysuitable means; for example, the stem may seat Within a cup 36 fixed tothe bimetal, being secured thereto by a pin 37 extending through the cupand stem. When the heat motor moves from a concave position to thatillustrated in FIG. 2 the pin 37 will lift the valve stem; when itreturns, the pin 37 will seat the valve. It will be understood that theheat motor operates in either direction with a snap action; heat motorsof this type are readily available commercially and may be obtained torespond to temperature conditions within the requirements of the presentduty.

Heat energy for the heat motor may be supplied by means of a resistanceheating element 38 disposed in a chamber 40 comprising a lower portionof the drainage fitting 31. Heating element 38 is advantageously of thefamiliar metal-sheathed resistance type such as disclosed in Oakley U.S.Patent 2,546,315, granted March 27, 1951, for Electric Heater. Suchheating elements have a tubular sheath of corrosion-resistant steel orequivalent Within which is a resistance, element embedded in a highlycompacted mass of a heat conducting, electrically insulating materialsuch as magnesium oxide. In the schematic showing of FIG. 2, theterminal portions 41, 42, of the heater extend through the bottom wallof the compartment 40 and. are welded or otherwise permanently securedthereto in fluid-tight relation.

The chamber 4% is sized to, contain about 4 ounces of a. heat transfermaterial which will conduct. heat from the heating element 38 to thebimetal disc 33. Preferably, the heat transfer material has a boilingpoint considerably above the boiling point of water, is somewhat heavierthan water, and has a relatively low specific heat. A suitable material,therefore, is glycerine, which boils at 290 C., has a specific heat of.6, and a density of 1.26.

For reasons later appearing, I wish to have the heat motor operate fromconcave to convex positionthat is, from valve closing to valve openingposition-in about five minutes, and wish to have the disc go fromconcave to convex at 240 F., and return to concave at about 140 F.Assuming that prior to the operation of the dishwater it has beenstanding in a normally heated room, it can be postulated that theglycerine will be at a temperature of 70 F. For the first operation ofthe valve from closed to open position, therefore, it will be necessaryto increase the glycerine temperature from 70 to 240 F. During thedishwasher operation, however, the glycerine will be at about F., andthis temperature will be used to calculate the necessary heat capacityof heater 38. To raise 4 ounces of glycerine 100 F., assuming thespecific heat of glycerine to be .6, requires .25 l00 .6, or 15 B.t.u.To accomplish this heating effort over a five minute period indicatesthe introduction of 3 B.t.u. per minute. Heat losses from the chamber40* and other heat losses may be as much as fifty percent, indicatingthat the thermal output of the element 41 should be of the order of 4.5Btu. per minute. At the commencement of operation of the dishwasher,when the glycerine is at a temperature which may be at least as low as70 F., a heat output of 4.5 B.t.u. per minute will necessarily require alonger period before the valve will open. The advantage of thisinitially longer period Will later be evident.

To maintain the chamber 40 in flooded condition with the glycerine incontact with the heat motor 33, I provide a short riser 40.1 (FIG. 1)extending to any appropriate height. The riser may be equipped with anysuitable capping device (not shown) to maintain the glycerine underatmospheric pressure so as to provide for free rise and fall as the heatmotor inverts its operating position.

The heat motor is operatively associated with a stepping switch by meansof which the total of washing and rinsing operations is established.This association is by way of a rod 44 fixed to the motor 33 by the cup45 and pin 46. The rod extends through a suitable gland 47 in the baseof chamber 50. The switch is in a housing 48 affixed beneath the chamber40 and comprises a ratcheting device and a bank of leaf-spring switchesto be operated thereby. For example, a bracket structure 49 has suitableupstanding bearing elements 50 supporting a ratchet 51 and an integralcam 52, said ratchet and cam being formed of nylon or other electricalinsulation material. The cam 52 has a cylindrical body portion 53 andtwo. diametrically opposite lobes 54, 54.1; the ratchet 51 has aplurality of ratchet teeth 55 sufficient to rotate the cam through in anumber of steps corresponding to the desired total of washing andrinsing operations.

The ratchet is operated in step-by-step fashion by art escapementmechanism which includes an escapement lever 56 pivotally attached to anupright fulcrum member 57 of the bracket 49, said lever mounting anescapement device 59, having the legs 60, 61 straddling the ratchet 51for engagement with the oppositely disposed teeth, as: shown. Theescapement device is mounted on the lever 56 ina manner which permits itto oscillate, and a leaf" spring or the like (not shown) between thelever and, the escapement device biases the device into counterclockwise rotation. Thus, when lever 56 is rotated up:-- wardly asviewed in FIG. 2 (as by the spring 62) escape-- ment leg 60 will snapover the ratchet tooth (not shown) immediately above the one shown; andon the downward. rotation of the lever 56 the escapement leg 60. willrotate the ratchet a distance of one tooth. The leg 61 interrupts. therotation by engagement with one of the teeth on the opposite portion ofthe ratchet. These ratcheting ar-- rangements are well known and widelyused. The down-- ward drive of the lever 56 takes place when the rod 44is driven downwardly bythe heat motor, for it will be noted that therounded tip ofrod 44 bears against the lever 56. Therefore, the size ofthe ratchet 51 as respects the angular spacing of its teeth must berelated to the movement of the valve stem.

There are two sets of switches in the switch stack. One set is operatedto open position by the cam lobe 54 or 54.1, but otherwise remainsclosed, and the other opensspring contact 70 is arranged for cooperationwith contact 68 to form the first of the switch pairs. As illustrated,the engagement of the nose 66 with either of the lobes 54 or 54.1 liftsthe spring contact 68 to open circuit position. When the nose rides onthe cylindrical body portion 53 of the cam the inherent bias of leafspring contact 68 brings it into circuit closing relationship withcontact 70.

An upper leaf spring contact 71 and a lower leaf spring contact 72comprise the second switch pair. An insulated finger 73 extends upwardlyfrom lever 56, whereupon when the lever is raised, as in FIG. 2, uppercontact 71 opens relative to contact 72.

In completion of the mechanical description of the stepping switch, itwill be noted that an extension of lever 56 projects through a slot 74in housing 48 and at its outer end is attached to an extremity 75 of thearmature of a solenoid 76. Said solenoid is arranged to be energized byactuation of momentary contact push-button switch 8 on the cabinet panel7; and as indicated in the schematic wiring diagram portion of FIG. 2,power can be applied to solenoid 76 only after the door latch 5 is madehome and its switch 6 is closed thereby.

It will be assumed that the dishwasher has been prepared for operationand the door 4 is closed. In this circumstance the heat motor 33 will becold and in its down position, thus closing the drain valve. The userstarts the dishwasher by momentarily closing switch 8 which energizesthe solenoid 76 through the conductors 77 and 78 drawing in its armatureto lift the lever 56. This, of course, snaps the heat motor upwardly andcocks the escapement mechanism for rotation of the ratchet. When thepushbutton switch is released to deenergize the solenoid 76, the heatmotor snaps back to its cold position, driving the lever 56 down againstthe return bias of spring 62. This completes the escapement operationand rotates the ratchet 51 and cam 52 one step. This brings the camfollower to the body portion 53 of the cam, closing switch contacts 68and 71). Because lever 56 is in its down position switch contacts 71 and72 are closed. A circuit is then completed through line conductor 80,motor 22, conductor 81, closed contacts 68, 7t), and conductor 82,closed switch 6, to line conductor 33. The motor 22 starts under no-loadconditions. The valve solenoid 12 is energizes through conductor 89,conductor 84, closed contacts 71 and 72, conductors 85 and 81, andclosed contacts 68, 70, to conductors S2 and 83. The heating element 38is energized through conductors 80 and 86, conductor 84, ClTSBd contacts71 and 72, conductors 85 and 81, closed contacts 68 and 70, andconductors 82 and 83. Therefore, the heater element is energized inparallel with the valve solenoid.

Water is now flowing into the dishwasher tub. After it accumulates tothe top of the inlet fitting 20 it will enter the pump 18, which at thattime is being driven at substantially operational speed by the motor 22.It will be obvious that at this time the motor is subjected only to theload imposed by the impellers of the fan 19 and pumps 18 and 23, andneither of these impellers is actually performing a pumping operation.The motor therefore starts under substantially no-load conditions. Waterflowing into the pump 18 will be discharged into the rotor 15 from whichit issues through the ports 16 to impinge on the dishes and the likewithin the tub. Water continues to flow into the tub and is recirculatedduring the entire washing operation. During this operation the heatingelement 38 is transferring heat to the heat motor 33. Because of theheat sink effect of the glycerine, as well as the capacity of the inletfitting to absorb heat, a substantial time elapses before the heatenergy transferred to the motor 33 is effective to cause it to snap toopen position. When the dishwasher is cold, this time may be of theorder of six to seven minutes; when the dishwasher is in operation, thetime lag may be of the order of five minutes. The six to seven minutedelay in the first operation is advantageous because usually water iscool as it first flows from the pipes into the dishwasher, and the cooldishes may further reduce the water temperature. The longer washingaction compensates for the somewhat low water temperature.

The spring 62 draws the actuating lever 56 upwardly as the valve stemmoves to its open-valve position, whereby the rod 44 cocks the ratchetfor the next step. As lever 56 rises, the insulating finger 73 separatescontacts 71 and 72 to deenergize the valve solenoid 12, interruptingwater flow into the tub 3, and deenergizing the heater 38. This iswithout effect on the power supply to the motor 22, which maintains itsoperation by way of the closed switch springs 68, 70.

The total water inlet to the dishwasher during a washing or rinsingoperation is from 12 to 14 pints. This amount of fill is established bythe use of a flow-control device (not shown) in the valve 10, as wellknown in the art. When the valve opens, water from the dishwasher tubfloods through the fitting 31 in heat transfer relation with the heatmotor 33. The discharging water is at a temperature of about Fahrenheitin the average domestic dishwasher, and after an interval which issufiicient to evacuate the wash water from the tub, the heat motor andthe glycerine will have lost sufiicient heat energy for the heat motorto restore to valve closing position. In so doing, of course, the valvestem and rod 44 are driven downwardly, completing the stepping of theratchet. The reclosing of leaf contacts 71 and 72 reopens the inletvalve to admit Water for the next washing operation, and heater 38 isreactivated. After about 5 minutes, the next valve opening occurs.

This action is repeated for the number of times necessary to accomplishthe desired number of washing and rinsing operations. In the usualdishwasher cycle two washes and two rinses are considered adequate.Therefore, the fourth cycling of the heat motor will actuate the valve25 to its closed position while ratcheting the cam 52 to cause the camfol ower portion of the lever 56 to rise on the lobe 54.1. breaking themotor and solenoid valve circuit and the heating element circuit at theswitch springs 63, 70.

While there has been described what is at present thought to be thepreferred embodiment of the invention, it will be understood thatvarious modifications may be made therein and it is intended to cover inthe appended claims all such modifications as fall within the truespirit and scope of the invention.

I claim as my invention:

1. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

a valve for introducing water into said tub;

means for operating said valve between closed and open positions;

a pump for circulating the water content of said tub among the articlesto wash the same;

a motor for operating said pump;

a circuit including switch means for energizing said motor;

a discharge conduit for evacuating water from said tub;

a valve in said discharge conduit;

motor means for operating said discharge valve between closed and openpositions; means responsive to a first opening and closing of saiddischarge valve to operate said first valve to open position and toclose said pump motor switch means;

means for actuating said valve operating means to operate said dischargevalve through a sequence of closed and open positions while maintainingsaid pump motor in operation;

means correlating said first and second valves to operate said firstvalve to closed position on opening said second valve and to openposition on closing said second valve;

means for tolling the number of times said valve is operated to closedposition; and

means responsive to a predetermined number of discharge valve operationsto open said pump motor switch means and to close said first and secondnamed valves.

2. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

a. valve for introducing Water into said tub;

electromotor means for operating said valve between closed and openpositions;

a pump for circulating the water content of said tub among the articlesto Wash the same;

a motor for operating said pump;

a circuit including switch means for energizing said motor;

a discharge conduit for evacuating water from said tub;

a valve in said discharge conduit;

motor means for operating said discharge valve between closed and openpositions;

means responsive to a first opening and closing of said discharge valveto operate said first valve to open position and to close said pumpmotor switch means;

means for actuating said valve operating means to opcrate said dischargevalve through a sequence of closed and open positions while maintainingsaid pump motor in operation;

means for tolling the number of times said valve is operated to closedposition; and

means responsive to a predetermined number of discharge valve operationsto open said pump motor circuit switch to deenergize said first namedvalve to close the same.

3. Dishwashing apparatus, comprising:

a tub to receive articles to be washed,

a valve for introducing water into said tub;

means for operating said valve between closed and open positions;

.a pump for circulating the water content of said tub among the articlesto wash the same;

.a motor for operating said pump;

a discharge conduit for evacuating water from said tub;

avalve in said discharge conduit;

thermally responsive means for operating said discharge valve betweenclosed and open positions;

a heating element in heat exchange relation to said discharge valveoperating means;

means for conjointly energizing said motor and said heating element;

means for operating said discharge valve through a sequence of closedand open positions while maintaining said pump motor in operation;

means for tolling the number of times said discharge valve is operatedbetween open and closed position;

means for closing said first named valve each time said discharge valveis opened; and

means for opening said pump motor circuit switch and for deenergizingsaid heating element after a predetermined number of operations of saiddischarge valve.

4. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

means for introducing water into said tub;

a first pump for circulating the water content of said tub among thearticles to wash the same;

a second pump for evacuating water from said, tub;

a motor for conjointly operating said first and second a chambercomprising an outflow passage communicating between said tub and saidsecond pump;

valve means disposed at the inlet of said chamber to control flow ofWater thereinto;

means in said chamber effective at a predetermined elevated temperatureto, open said valve means for flow of Water from said tub into andthrough said chamber to said second pump and effective at apredetermined lower temperature to close said valve means;

a heating element in said chamber;

means for energizing said element;

means providing a heat sink interposed between said heating element andsaid valve actuating means to delay the increase in temperature thereofto valve opening level;

said valve actuating means being in the path of water flow through saidchamber to give up heat to said water during flow thereof to said secondpump whereby the temperature of said valve actuating means is reduced tovalve closing temperature; and

means effective upon an operation of said valve to closed position toterminate the operation of said motor.

5. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

means for introducing water into said tub;

a pump for circulating the water content of said tub among the articlesto wash the same;

means for evacuating water from said tub;

a motor for operating said pump;

an energizing circuit for said motor;

a chamber comprising an outflow passage communieating between said tuband said water evacuation means;

valve means disposed at the inlet of said chamber to control flow ofwater thereinto;

a heat motor effective at a first heat energy condition to open saidvalve means for flow of water into and through said chamber to saidevacuation means and elfective at a second heat energy condition toclose said valve means;

means to supply heat energy to said motor;

means providing a heat sink interposed between said heat energy supplyand said heat motor to delay the attainment of said first heat energycondition;

said heat motor being arranged to give up heat to the water flowing tosaid water evacuation means whereby to establish the heat energy in saidmotor at the. second condition; and

switch means responsive to movement of said valve to closed position toopen said pump motor circuit and deenergize said heat energy source.

6. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

means for introducing water into said tub;

a first pump for circulating the water content of said:

tub among the articles to Wash the same;

a second pump for evacuating water from said tub;

a motor for conjointly operating said first and second a chambercomprising an outflow passage communicating between said tuband saidsecond pump;

valve means disposed at the inlet of said chamber to; control flow ofwater from said tub thereinto;

a heat motor in said chamber, said motor being effective at a firstlevel of heat energy to open said valve means for flow of water into andthrough said chamber to said second pump and effective at asubstantially lower second level of heat energy to close said valvemeans;

a source of heat energy;

means for energizing said energy source; and

means comprising a heat transfer fluid in heat exchange relation withsaid energy source and said heat motor to provide a heat sink to delaythe increase in heat energy therein to said first level,

said heat transfer fluid heat motor being arranged to give up heat tothe water flowing through said chamber whereby the heat energy in saidheat motor is, reduced to said second level to close said valve.

7-. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

means for introducing water into said tub;

means for circulating water among the articles in said tub for washingthe same;

a drainage conduit for draining water from said tub;

a valve at the entrance of said conduit;

valve actuator means including a heat motor and a shaft movable by saidheat motor under one condition thereof to operate said valve to opencondition and movable by said heat motor under a second conditionthereof to operate said valve to closed condition;

heat transfer means operatively associated with said heat motor toestablish the respective first and second conditions thereof;

means for cycling said valve between closed and open positions; and

means responsive to a predetermined number of operations of said valveto closed position to terminate the operation of said heat motor tomaintain the valve in closed position.

8. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

means for introducing water into said tub;

means for circulating water among the articles in said tub for washingthe same;

a drainage conduit for draining water from said tub;

a valve at the entrance of said conduit;

valve actuator means including a heat motor having a shaft movable bysaid heat motor under one condition thereof to operate said valve toopen condition and movable by said heat motor under a second conditionthereof to operate said valve to closed condition;

electric resistance means in heat transfer relation with said heat motorto establish the said first condition thereof;

means for transferring heat from said heat motor to the water drainingfrom said tub to establish said second condition thereof;

a switch for controlling electric energy to said electric resistancemeans; and

a stepping mechanism actuated by said heat motor shaft to open saidswitch after a predetermined number of movements of said shaft.

9. Dishwashing apparatus according to claim 8, in

which said heat motor comprises a bimetallic disc selfbiased to returnsaid valve to closed position when cooled by the water passing throughsaid conduit.

10. Dishwashing apparatus, comprising:

a tub to receive articles to be washed;

an inlet valve for introducing water into said tub;

electromot'or means for operating said valve from a normally closedposition to an open position;

a pump for circulating water among the articles in said pump for washingthe same;

a motor for operating said pump;

a drainage conduit for draining water from said tub;

a drain valve at the entrance to said conduit;

drain valve actuator means including a heat motor and a shaft movable bysaid heat motor under a first heat energy condition to operate saidvalve to open con dition and movable by said heat motor under a secondheat energy condition to operate said valve to closed condition;

electric resistance means in heat transfer relation with said heat motorto produce said first heat energy condition therein;

means for effecting heat transfer from said heat motor to water in saiddrainage conduit to produce said second heat energy condition in saidheat motor;

an electric energy circuit for conjointly energizing said inlet valve,said pump motor, and said resistance means;

switch means in said energy circuit;

means for initially closing said switch means;

a cam for operating said switch means to open position;

a ratcheting device responsive to each operation of said heat motorshaft to advance said cam toward switchopening position, whereby after apredetermined number of said operations the energy circuit is opened toterminate operation of the components deriving energy therefrom.

References Cited in the file of this patent UNITED STATES PATENTS1,995,635 Clark Mar. 26, 1935 2,669,240 Thorson Feb, 16, 1954 2,825,348Low Mar. 4, 1958

1. DISHWASHING APPARATUS COMPRISING: A TUB TO RECEIVE ARTICLES TO BEWASHED; A VALVE FOR INTRODUCING WATER INTO SAID TUB; MEANS FOR OPERATINGSAID VALVE BETWEEN CLOSED AND OPEN POSITIONS; A PUMP FOR CIRCULATING THEWATER CONTENT OF SAID TUB AMONG THE ARTICLES TO WASH THE SAME; A MOTORFOR OPERATING SAID PUMP; A CIRCUIT INCLUDING SWITCH MEANS FOR ENERGIZINGSAID MOTOR; A DISCHARGE CONDUIT FOR EVACUATING WATER FROM SAID TUB; AVALVE IN SAID DISCHARGE CONDUIT; MOTOR MEANS FOR OPERATING SAIDDISCHARGE VALVE BETWEEN CLOSED AND OPEN POSITIONS; MEANS RESPONSIVE TO AFIRST OPENING AND CLOSING OF SAID DISCHARGE VALVE TO OPERATE SAID FIRSTVALVE TO OPEN POSITION AND TO CLOSE SAID PUMP MOTOR SWITCH MEANS; MEANSFOR ACTUATING SAID VALVE OPERATING MEANS TO OPERATE SAID DISCHARGE VALVETHROUGH A SEQUENCE OF CLOSED AND OPEN POSITIONS WHILE MAINTAINING SAIDPUMP MOTOR IN OPERATION; MEANS CORRELATING SAID FIRST AND SECOND VALVESTO OPERATE SAID FIRST VALVE TO CLOSED POSITION ON OPENING SAID SECONDVALVE AND TO OPEN POSITION ON CLOSING SAID SECOND VALVE; MEANS FORTOLLING THE NUMBER OF TIMES SAID VALVE IS OPERATED TO CLOSED POSITION;AND MEANS RESPONSIVE TO A PREDETERMINED NUMBER OF DISCHARGE VALVEOPERATIONS TO OPEN SAID PUMP MOTOR SWITCH MEANS AND TO CLOSE SAID FIRSTAND SECOND NAMED VALVES.